Voice Over IP (VOIP) is a family of technologies that enable the transmission of voice communications over the Internet. VOIP uses well known Internet protocols and VOIP telephony protocols to transmit voice data. Examples of Internet protocols used by VOIP include the Transmission Control Protocol (TCP) and the Real-time Transport Protocol (RTP). Examples of VOIP telephony protocols include the Session Initiation Protocol (SIP), the H.323 standard, and the Skinny Call Control Protocol (SCCP), which is owned and defined by Cisco Systems, Inc.
Many monitoring solutions attempt to provide voice quality metrics by passively monitoring Internet Protocol (IP) Packet Metrics traversing the network. Such solutions involve hardware and/or software components that sit on the network and monitor data traffic as that traffic flows through the network. These solutions are accordingly limited to whatever happens to be traversing the network at any given time, which may not give the entity performing the monitoring an adequate sense of how the network and its various components are really performing. Because of the passive nature of such solutions, they are only capable of performing Mean Opinion Scores (MOS) tests on the monitored data and cannot perform Perceptual Evaluation of Speech Quality (PESQ) tests, which would require a known transmitted prompt to be compared to the received prompt or to a reference prompt. PESQ is an existing family of standards used within the telecommunications industry comprising a test methodology for the automated assessment of speech quality as experienced by a user of a telephony system. PESQ is a full reference algorithm which can compare each sample of the reference signal, from the speaker side, to each corresponding sample of the degraded signal, on the listener side. Specifically, PESQ analyzes the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of reference signals and test signals. PESQ results usually model Mean Opinion Scores (MOS).
Other attempts at providing voice quality metrics have limited functionality by only working within specific infrastructures instead of working in any telephony environment. For example, such solutions are only capable of performing tests within an internal network, but are not capable of performing calling tests from outside of the network into the network or from inside of the network to outside of the network.